In a prior clamp according to DE-GM 91 01 321, there are two approximately equal clamp components and a pressure disc positioned between them, the whole assembly being penetrated by a centrally positioned threaded screw of a loading device. The loading device rests on the top clamp component, and is screwed into the bottom clamp component. The clamp components have two semi-cylindrical recesses that serve to hold rod shaped construction components. With this clamp two construction components can be permanently connected. Thus, for example, a carbon filament rod and a Schanz screw, are each inserted between a clamp component and the pressure disc, and clamped by the threaded screw, which has a rotary head. The actual gripping power brought to bear on the rod depends on the ratio of the distance between the axis of the loading device and the axis of the rod to the distance between the axis of the loading device and the support of the clamping component of the pressure disc. In order to achieve the most effective possible grip on the rod for a given loading device, according to the law of leverage, the aforementioned ratio must be as small as possible. The consequence is that the gripping components are inevitably larger in size. These gripping connections, used particularly for external fixation in osteosynthesis, are used chiefly for setting small parts of the body, a use in which the gripping components must not be too large. In practice, it has been found that for the reasons indicated the gripping power achieved with clamps of the type described is not firm enough, and thus a secure bracing between the construction components or the setting device as a whole is not achieved. In addition, it often happens that the gripping power weakens after a certain time and thus fixation no longer exists at all.
Another gripping device, described in WO-A1 88/01152, provides for gripping discs similar to that described above. A pair of these gripping discs position a screw or similar device in semi-circular recesses and grip it by means of a screw positioned axially to them. To hold two construction components, two pairs of such gripping discs are provided for one loading screw. Theoretically, this gripping device has the same disadvantages as the device described above, because the gripping power actually exerted on a rod similarly assumes an unfavorable ratio of distance between the axis of the bracing screw and the support of the gripping discs. This is not altered by the construction of the gripping discs on the support with toothed gearing provided on each side. In this known, open system, the oblique plane present is used not to improve the grip but merely to improve the centering between the connection and the gripping component.